A method for detecting fuel injectors in cold test of automobile engines

Abstract

The present invention discloses a method for detecting an injector in a cold test of an automobile engine, including controlling the engine to run to a set speed and maintaining it through a servo motor; using an ECU to receive signals from various sensors of the engine and autonomously control the injection amount and injection position, so that the engine performs compression ignition and work; and evaluating the engine injector and fuel supply system by detecting the combustion torque data of the engine and the rail pressure change. The correctness and integrity of the data written in the ECU are detected through autonomous control of the ECU, which is closer to the actual control situation of the engine, more precise than the control of the host computer, and the action process is faster. Since its control method is closed-loop control, it makes up for the defects of the open-loop control of the host computer.

Description

Technical Field

[0001] The invention relates to a fuel injector testing technology, in particular to a fuel injector testing method in a cold test of an automobile engine. Background Art

[0002] At present, there are many ways to detect the injector in the cold test of automobile engines, but they are only to detect whether the injector can spray fuel or whether the electrical performance is good. It mainly determines the compression ignition top dead center of the engine through the host computer, controls the rail pressure, sets the injection time, performs quantitative injection, and evaluates the fuel system through the combustion torque test (combustion torque is the torque generated when the engine is compressed and ignited). However, this method does not have any substantial detection of whether it can match the data in the ECU (engine electronic control unit) of the engine and whether the injection atomization effect is good.

[0003] In summary, the existing injector detection method has the following defects:

[0004] 1. It is not possible to test whether the data in the ECU has been flashed;

[0005] 2. It is not possible to test whether the data written into the ECU is correct;

[0006] 3. It cannot simulate the actual operation state of the engine;

[0007] 4. The accuracy and speed of host computer control are not ideal. Summary of the invention

[0008] In order to solve the above problems in the prior art, the present invention provides a method for detecting a fuel injector in a cold test of an automobile engine, which uses an ECU instruction to perform a fuel injection action and performs compression ignition only once to analyze the combustion torque for testing.

[0009] A method for detecting a fuel injector in a cold test of an automobile engine of the present invention comprises the following steps:

[0010] a. Control the engine to run to the set speed and maintain it through the servo motor;

[0011] b. The ECU receives signals from various engine sensors and autonomously controls the injection amount and injection position, allowing the engine to perform compression ignition and work;

[0012] c. Evaluate the engine injector and fuel supply system by detecting the engine's combustion torque data and rail pressure changes and comparing them with the corresponding set thresholds.

[0013] In step b, the sensors include a crankshaft position sensor, a cam position sensor, a combustion torque sensor and a rail pressure sensor.

[0014] In step b, the injection position is determined and controlled by the relationship between the crankshaft position sensor and the cam position sensor, and the injection amount is adjusted by the logical relationship set in the ECU.

[0015] In step c, the combustion torque data includes the maximum value and minimum value of the torque and the angular positions corresponding to the maximum value and minimum value.

[0016] In step c, the rail pressure variation includes the speed of increasing and decreasing the pressure during fuel injection.

[0017] In step c, the combustion torque data of the engine is measured by a torque sensor.

[0018] The following beneficial effects are achieved by using the fuel injector detection method in a cold test of an automobile engine according to the present invention:

[0019] 1. The correctness and integrity of the flash data in the ECU were detected through ECU autonomous control;

[0020] 2. ECU autonomous control is closer to the actual control situation of the engine;

[0021] 3. ECU autonomous control is more precise than host computer control, and the action process is faster. Since its control method is closed-loop control, it makes up for the defects of host computer open-loop control. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a principle block diagram of the fuel injector detection method of the present invention;

[0023] Figure 2 A graph showing the combustion torque and rail pressure changes obtained by detecting an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The following is a further description of a method for detecting a fuel injector in a cold test of an automobile engine according to the present invention in conjunction with the accompanying drawings and embodiments.

[0025] like Figure 1 As shown, a method for detecting a fuel injector in a cold test of an automobile engine of the present invention specifically comprises the following steps:

[0026] a. Use the equipment servo motor to drag the engine to the specified speed, and instruct the servo motor to always maintain this speed. The set speed of different engines is different and is set and provided by the engine manufacturer;

[0027] b. The ECU receives signals from various sensors of the engine, including the crankshaft position sensor, cam position sensor, rail pressure sensor, etc., and autonomously controls the injection amount and injection position, so that the engine performs compression ignition and work. The injection position is determined by the relationship between the crankshaft position sensor and the cam position sensor, and the injection amount is adjusted by the logical relationship set in the ECU. These are all logical relationships within the ECU, which are set and provided by the engine manufacturer.

[0028] c. The combustion torque data and rail pressure change of the engine are detected by the torque sensor and rail pressure sensor respectively, and input into the PC for comparison with the corresponding set threshold (provided by the engine manufacturer) to evaluate the engine injector and fuel supply system. The combustion torque data includes the maximum and minimum values ​​of the torque and the angular position corresponding to the maximum and minimum values ​​(i.e. the position of the engine in a cycle, such as the position of a six-cylinder engine in 720 degrees); the rail pressure change includes the speed of injection pressure increase and decrease.

[0029] Example

[0030] The method of the present invention is used to detect a certain type of six-cylinder engine. The engine is kept at a speed of 300R / Min by a servo motor. The ECU is used to autonomously control the injection amount and injection position so that the engine performs compression ignition and work. The maximum and minimum values ​​of the torque, the angular positions corresponding to the maximum and minimum values, and the speed of injection pressure increase and decrease are obtained by detection. Figure 2 As shown, the arrangement order of the waveforms in the figure is arranged according to the engine working order: one cylinder, five cylinders, three cylinders, six cylinders, two cylinders, and four cylinders. The set thresholds of the engine are as follows:

[0031] The maximum value range of the combustion torque of each cylinder is: 450N ~ 750N; the minimum value range of the combustion torque of each cylinder is: -1350N ~ -1650N; the angle position range corresponding to the maximum value of the combustion torque of the first cylinder is: 17° ~ 23°; the angle position range corresponding to the maximum value of the combustion torque of the second cylinder is: 497° ~ 503°; the angle position range corresponding to the maximum value of the combustion torque of the third cylinder is: 257° ~ 263°; the angle position range corresponding to the maximum value of the combustion torque of the fourth cylinder is: 617° ~ 623°; the angle position range corresponding to the maximum value of the combustion torque of the fifth cylinder is: 137° ~ 143°; the angle position range corresponding to the maximum value of the combustion torque of the sixth cylinder is: 137° ~ 143°; The angular position range corresponding to the maximum value of the combustion torque of the cylinder is: 377°~383°; the position range of the minimum value of the combustion torque of cylinder one is: 72°~78°; the position range of the minimum value of the combustion torque of cylinder two is: 529°~535°; the position range of the minimum value of the combustion torque of cylinder three is: 288°~294°; the position range of the minimum value of the combustion torque of cylinder four is: 648°~654°; the position range of the minimum value of the combustion torque of cylinder five is: 193°~198°; the position range of the minimum value of the combustion torque of cylinder six is: 432°~438°; the speed range of fuel injection pressure increase and decrease is 5-15bar / ms.

[0032] according to Figure 2From the combustion torque curve (line A) and rail pressure curve (line B) shown in the figure, it can be seen that the maximum value of the combustion torque of the first cylinder is 501NM, and the minimum value is -1531NM; the maximum value of the combustion torque of the second cylinder is 493NM, and the minimum value is -1520NM; the maximum value of the combustion torque of the third cylinder is 488NM, and the minimum value is -1526NM; the maximum value of the combustion torque of the fourth cylinder is 480NM, and the minimum value is -1513NM; the maximum value of the combustion torque of the fifth cylinder is 495NM, and the minimum value is -1536NM; the maximum value of the combustion torque of the sixth cylinder is 499NM, and the minimum value is -1508NM. The maximum value position of the combustion torque of cylinder one is 19°, and the minimum value position is 75°; the maximum value position of the combustion torque of cylinder two is 500°, and the minimum value position is 531°; the maximum value position of the combustion torque of cylinder three is 259°, and the minimum value position is 290°; the maximum value position of the combustion torque of cylinder four is 619°, and the minimum value position is 651°; the maximum value position of the combustion torque of cylinder five is 140°, and the minimum value position is 195°; the maximum value position of the combustion torque of cylinder six is ​​388°, and the minimum value position is 436°. The pressure reduction speed of one-cylinder fuel injection is 9bar / ms, and the pressure increase speed is 7bar / ms; the pressure reduction speed of two-cylinder fuel injection is 10bar / ms, and the pressure increase speed is 8bar / ms; the pressure reduction speed of three-cylinder fuel injection is 7bar / ms, and the pressure increase speed is 7bar / ms; the pressure reduction speed of four-cylinder fuel injection is 11bar / ms, and the pressure increase speed is 6bar / ms; the pressure reduction speed of five-cylinder fuel injection is 10bar / ms, and the pressure increase speed is 7bar / ms; the pressure reduction speed of six-cylinder fuel injection is 9bar / ms, and the pressure increase speed is 7bar / ms.

[0033] Since all the measured values ​​are within the above threshold range, the injector and fuel supply system of the engine are determined to be qualified.

[0034] In summary, the injector detection method of the present invention can effectively improve the accuracy of the injection amount and injection time due to the introduction of ECU instructions for injection and compression ignition, and has a fast rail pressure control capability, and is more realistically close to the state of the engine when it is running by itself.

[0035] However, those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A method for detecting a fuel injector in a cold test of an automobile engine, characterized in that: The following steps are involved: a. Control the engine to run to the set speed and maintain it through the servo motor; b. The ECU receives signals from various engine sensors and autonomously controls the injection amount and injection position, allowing the engine to perform compression ignition and work; c. Evaluate the engine injector and fuel supply system by detecting the engine's combustion torque data and rail pressure changes and comparing them with the corresponding set thresholds.

2. A method for detecting a fuel injector in a cold test of an automobile engine as claimed in claim 1, characterized in that: In step b, the sensors include a crankshaft position sensor, a cam position sensor and a rail pressure sensor.

3. A method for detecting a fuel injector in a cold test of an automobile engine as claimed in claim 2, characterized in that: In step b, the injection position is determined and controlled by the relationship between the crankshaft position sensor and the cam position sensor, and the injection amount is adjusted by the logical relationship set in the ECU.

4. A method for detecting a fuel injector in a cold test of an automobile engine as claimed in claim 1, characterized in that: In step c, the combustion torque data includes the maximum value and minimum value of the torque and the angular positions corresponding to the maximum value and minimum value.

5. The method for detecting a fuel injector in a cold test of an automobile engine as claimed in claim 1, characterized in that: In step c, the rail pressure variation includes the speed of increasing and decreasing the pressure during fuel injection.

6. A method for detecting a fuel injector in a cold test of an automobile engine as claimed in claim 1, characterized in that: In step c, the combustion torque data of the engine is measured by a torque sensor.

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